There are different versions of Tableau. 

• Tableau Public, the free program, has limitations on the size of data, types of data, and publishing rights. With Tableau public, you can only save work to the web, which means you can not share visualizations you created with private data, such as data retrieved from library databases.
• Tableau Desktop is not free, but faculty and students can get it for instruction or learning. It allows you to save files privately and has no data size limits.

You can download Tableau Public or obtain a one year Tableau student license. Faculty can obtain a Tableau license for teaching.